Study On Preparation And Properties Of TiO₂ Nano Materials With Different Microstructures

TiO2 nano materials has been widely used in the photocatalysis field because it's stable chemical properties, non pollution, low cost and no selective degradation to organic pollution. TiO2 also has a lot of disadvantages, such as the low quantum efficiency, the wide band gap (band gap is 3.2eV), and the smaller surface area, thus limit its application in industry. Therefore, the modification of TiO2 nano materials has been widely concerned, in recent years, through the regulation of crystal surface structure to improve the TiO2 quantum efficiency has become a hot research topic.In this paper, we are committed to expose the high active crystal surface of TiO2 in the way of microstructure control. Using hydrothermal method prepared TiO2 nano materials with different crystal surfaces, also studied it's microstructure, spectroscopy performance and photocatalytic properties, and discussed the optimum preparation conditions. In order to further improve the photocatalytic performance of TiO2 nano materials, TiO2 with high exposure rate of (001) crystal surface were prepared, also studied it's microstructure, spectroscopy performance and photocatalytic properties, and obtained the following results:First, the prepared mesoporous TiO2 nano materials were anatase phase, the average particle size is about 7nm and all have the Langmuir type IV pore structure. The best preparation condition:hydrothermal temperature is 160?, hydrothermal time is 24h, mesoporous TiO2 has the BET surface area of 146m2/g, it's photocatalytic degradation rate is 97.07% in an hour(the dosage of TiO2 is 0.25g).Second, using hydrofluoric acid and ammonium fluoride as crystal control agent can exposed (001) crystal face of TiO2, the sample morphology is a truncated eight plane double cone structure, particle size is about 20-30nm, and it can be seen that the mesoporous structure formed by the accumulation of particles. The presence of F- on the sample surface broadened the light response range of the (001) crystal face TiO2 in a certain extent. The best preparation condition:hydrothermal temperature is 180?, the volume of hydrofluoric acid is 0.5mL, the amount of ammonium fluoride is 0.5g, photocatalytic degradation rate of TiO2 is 98.29% in an hour(the dosage of TiO2 is 0.25g).Third, using hydrofluoric acid as crystal control agent, prepared (001) facets TiO2(exposure rate is 55.2%) nano sheet by changing the conditions of hydrothermal method. The prepared samples has strong UV photocatalytic activity and visible light photocatalytic activity. The best preparation condition:hydrothermal temperature is 180?, hydrothermal time is 24h and the molar ratio of F/Ti is 1.5, (001) facets TiO2 showed the highest photocatalytic activity, its photocatalytic degradation rate is 99.08% and 66.79% in an hour(the dosage of TiO2 is 0.25g) under UV light and visible light irradiation, correspondingly.